A magnetic storm of G4 class occurred on the Earth on January 19-21, 2025. The proton event, accompanying the storm, has been the strongest one for the XXI century

Space weather was commented on by the researchers of Paratunka Complex Geophysical Observatory of IKIR FEB RAS, Cand. Sci. (Phys.-Math.) Khomutov Sergey Yurevich and Cand. Sci. (Tech.) Gvozdarev Alexey Yurevich: «The source of the storm was a coronal mass ejection accompanying an X-ray flare (X1.95) occurred one day before (the radiation maximum was at 18:09 UT on January 18, 2026). A sudden commencement of the magnetic storm (field northern component jumped by 60 nTl at mid latitudes, that occurred as the result of magnetosphere compression by plasma cloud) was recorded at 19:17 UT on January 19, 2026, when Kamchatka people were going to work (the time difference with UT is 12 hours). The proton event, accompanying the storm commencement, was the strongest one in the XXI century. Solar wind velocity at the disturbance front was 1100 km/s (it is usually about 300 km/s)».

Fig. 1 shows the location of IKIR Geophysical Observatories: Mys Shmidta (Cape Shmidt), Magadan, Paratunka and Khabarovsk.

Fig. 2 shows geomagnetic variation measurements at these four observatories (upper panel) and local indexes of geomagnetic activity for each observatory (lower panel).

It is clear from the graphs, presented by our researchers, that this storm had the highest disturbance index (K=9) for the Far East. It is also clear that the disturbances in the polar latitudes (Mys Shmidta) were the strongest and reduced as the latitude decreased.

«We would like to emphasize the fact that measurements at IKIR FEB RAS observatories cover both high and middle latitudes showing the features of geomagnetic disturbances at different latitudes. For example, during the storm commencement, a sudden fall of the northern component by more than 3000 nTl was observed. It was probably caused by particle precipitation from radiation belts» - the researchers explained.

Re-activation of geomagnetic activity was observed after 07:27 UT on January 20, 2026, when the Earth entered the region with the southern polarity of interplanetary magnetic field. Kamchatka people could observe aurora on that night and a day after. The storm lasted until 18:00 on January 21.